Namelist parameters and diagnostics

Namelist parameters

Icebergs are enabled with do_icebergs=.TRUE. in the ice_model_nml namelist of SIS1 or DO_ICEBERGS=True in the SIS_input parameter file of SIS2.

Namelist variables for controlling the iceberg model are provided in the icebergs_nml namelist and include:

• initial_mass: initial mass for each class of iceberg (real vector)
• initial_depth: initial total thickness for each class of iceberg (real vector)
• distribution: the fraction of calving flux accumulated in each class (real vector)
• mass_scaling: virtual scaling for each class (real vector)
• LoW_ratio: ratio L/W for newly calved icebergs (real) [default 1.5]
• rho_bergs: density of iceberg ice (real) [default 850 kg/m^3]
• bergy_bit_erosion_fraction: fraction (0..1) of iceberg erosion flux to re-direct into bergy bits (real) [default 0.0]
• sicn_shift: added to sea-ice concentration in modulating function for erosion flux (real) [default 0.0]
• use_operator_splitting: if true, use simple, first order operator splitting to update the iceberg mass budget (logical) [default T]
• halo: halo width for gridded fields (integer) [default 4]
• traj_sample_hrs: interval in hours between sampling of icebergs positions, 0 is off (integer) [default 24]
• verbose: if true, reports some information to tty (logical) [default F]
• verbose_hrs: interval in hours between verbose message to tty, 0 is off (integer) [default 24]
• budget: if true, calculate global mass budgets and statistics (logical) [default T]
• parallel_reprod: if true, sorts the icebergs into a particular order to ensure reproducibility across PE decompositions (logical) [default T]
• use_slow_find: if true, uses a brute force approach for finding the (i,j) cell for an iceberg - this is robust but slow (logical) [default F]
• ignore_ij_restart: if true, ignores the (i,j) position in the restart file. This allows restarts to be used on different horizontal grids. (logical) [default F]
• add_weight_to_ocean: if true, adds weight of icebergs to pressure loading on ocean (logical) [default T]
• passive_mode: if true, makes icebergs completely passive, so that they do not affect coupled model (logical) [default F]
• ignore_ij_restart: if true, will ignore the i,j location data in the restart file (needed for changing grids). If false, speeds up restarts. [default F]
• time_average_weight: if true, time-averages the weight of icebergs felt by the ocean. [default F]
• generate_test_icebergs: if true, initialize with a prescribed test distribution of bergs (for testing code) [default F]
• speed_limit: speed_limit: if >0, limits the speed of bergs to a local CFL = speed_limit [default 0.0]
• fix_restart_dates: if true, check that restart bergs were created before the current model date [default T]
• use_roundoff_fix: if true, use a "fix" for the round-off discrepancy between is_point_in_cell() and pos_within_cell() [default T]
• old_bug_rotated_weights: if true, does not properly rotate the off-center weights for halo-updates [default F]

Diagnostics

Static variables available for output using the ''diag_table'' are:

• area: (static) cell area
• lat: (static) latitude of corner nodes
• lon: (static) longitude of corner nodes
• mask: (static) land-sea mask

Time-dependent variables available for output using the ''diag_table'' are:

• mass: iceberg density (mass per unit area)
• bergy_mass: bergy bits density (mass per unit area)
• melt: iceberg + bits melt/erosion flux (seen by the ocean)
• berg_melt: iceberg melt + erosion flux
• bergy_melt: bergy bits melt flux
• melt_buoy: buoyancy component of iceberg melt water flux into the ocean
• melt_eros: erosion component of iceberg melt water flux into the ocean
• melt_conv: convective component of iceberg melt water flux into the ocean
• bergy_src: bergy bits creation flux (fraction of erosion)
• virtual_area: virtual surface area of icebergs (m^2 per cell)
• accum_calving: calving used up by icebergs model
• unused_calving: unused calving returned to sea-ice model
• calving: calving provided by SIS
• real_calving: calving of stored-ice components into real icebergs
• sst: sea-surface temperature
• uo: u component of ocean velocity
• vo: v component of ocean velocity
• ui: u component of sea-ice velocity
• vi: v component of sea-ice velocity
• ua: u component of atmosphere velocity
• va: v component of atmosphere velocity
• cn: sea-ice concentration
• hi: sea-ice thickness

Necessary scripting mods

To combine iceberg restart and trajectory files you can not use mppnccombine. Instead add this to your XML: [@cd $work/RESTART ncrcat icebergs.res.nc.* icebergs.res.nc rm -f icebergs.res.nc.*

cd $work ncrcat iceberg_trajectories.nc.* iceberg_trajectories.nc rm -f iceberg_trajectories.nc.*@]

Example namelist for XML

<namelist name="ice_model_nml">
   do_icebergs = .true.
</namelist>
<namelist name="icebergs_nml">
   verbose=.TRUE.
   traj_sample_hrs=24
   verbose_hrs=24
</namelist>